RecruitingNot ApplicableNCT07159035

Flexible Ureteroscopy With a Flexible and Navigable Suction Ureteral Access Sheath Versus Mini-Percutaneous Nephrolithotomy for 1-2 cm Lower Pole Kidney Stones

Flexible Ureteroscopy With a Flexible and Navigable Suction Ureteral Access Sheath Versus Mini-Percutaneous Nephrolithotomy for 1-2 cm Lower Pole Renal Stones: an International, Multicenter, Randomized Non-Inferiority Trial (FLAME Trial)

Sponsor

The First Affiliated Hospital of Guangzhou Medical University

Enrollment

640 participants

Start Date

Aug 28, 2025

Study Type

INTERVENTIONAL

Conditions

Kidney Stones

Summary

This study, known as the FLAME Trial (Flexible ureteroscopy for Lower pole stones And Mini-pErcutaneous nephrolithotomy), is an international, multicenter, randomized, non-inferiority trial. It aims to compare the effectiveness and safety of flexible ureteroscopy using a flexible and navigable suction ureteral access sheath (FANS) versus mini-percutaneous nephrolithotomy (mini-PCNL) in the treatment of 1-2 cm lower pole kidney stones. A total of 640 eligible adult patients will be enrolled across 20 high-volume urology centers in China, Russia, Turkey, and India. Participants will be randomly assigned to undergo either FANS-assisted flexible ureteroscopy or mini-PCNL. The primary outcome is the immediate stone-free rate (SFR) assessed by non-contrast CT within 72 hours after surgery. Secondary outcomes include SFR at 1 month, operative time, pain score, length of hospital stay, complication rates, and changes in health-related quality of life. The goal of this trial is to determine whether the less invasive FANS-assisted approach is non-inferior to mini-PCNL in terms of efficacy, while potentially offering advantages in postoperative recovery and safety.

Eligibility

Min Age: 18 YearsMax Age: 75 Years

Inclusion Criteria4

Adults aged 18-75 years;
American Society of Anesthesiology (ASA) score 1-3;
Lower pole renal stones-single or multiple-with a maximal diameter of 1-2 cm confirmed by CT;
Ability to provide written informed consent and adhere to trial requirements.

Exclusion Criteria10

Significant urinary tract anatomical anomalies (e.g. horseshoe kidney, ileal conduit);
Stones located within a calyceal diverticulum;
History of open nephrolithotomy or ureterolithomy (due to resultant intrarenal anatomical distortion);
Absolute contraindications to either FANS-f-URS or mini-PCNL, including:
Uncorrectable coagulopathy;
Active, uncontrolled urinary tract infection;
Severe cardiopulmonary disease precluding safe general anesthesia (e.g. decompensated heart failure, refractory COPD);
Pregnancy;
Inability to tolerate lithotomy or prone positioning;
Inability to understand or complete trial documentation.

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Interventions

PROCEDUREFlexible ureteroscopy with FANS

The FANS with negative-pressure suction, enhancing intrarenal pressure control and fragment evacuation during flexible ureteroscopy.

PROCEDUREMini-percutaneous nephrolithotomy (mini-PCNL)

Mini-PCNL is performed under general anesthesia with less than 20 Fr access tract, using rigid nephroscopy and stone fragmentation under direct visualization. Postoperative drainage is provided via nephrostomy or ureteral stent as per protocol.